Yuji Suto

Fatal air embolism as a complication of CT-guided needle biopsy of the lung.

A CT-guided needle lung biopsy carries a risk of potential air embolization. We present a rare case of air embolization after this procedure. Postmortem CT revealed air in the cerebral arteries and the left ventricle. This complication is extremely rare; however, it becomes fatal when it happens. Several points to prevent this fatal complication are discussed.

Mechanism of action and therapeutic indication of prosthetic mandibular advancement in obstructive sleep apnea syndrome.

Abstract Prosthetic mandibular advancement (PMA) was applied to nine patients with obstructive sleep apnea syndrome (OSAS) and its therapeutic usefulness, mechanism of action, and clinical indication were discussed based on polysomnographic findings and serial examination of upper airway before and during PMA treatment. Apnea hypopnea index significantly decreased during PMA treatment compared with the value before treatment (P < 0.01) and the rate of the treatment responder counted 78.1%. Cephalometric variables indicated forward and inferior advancement of mandible in our subjects. Magnetic resonance imaging of the upper airway during sleep revealed a marked improvement of velopharyngeal obstruction in most subjects. In addition, intraesophageal negative pressure during sleep decreased significantly. Our results confirmed the high therapeutic efficacy of PMA for OSAS and indicated forward advancement of the mandible and decrease of negative pressure loading on upper airway with PMA might suppress velopharyngeal collapse. Thus, PMA was regarded as one of the treatments of choice for OSAS occurring based on with velopharyngeal narrowing.

Age-related changes in cerebral lactate metabolism in sleep-disordered breathing

Thirty-one patients, aged 22-71 years, with nocturnal apneic episodes and/or habitual snoring were studied with magnetic resonance spectroscopy (MRS) and diagnostic polysomnography separately to determine whether accumulation of lactate caused by cerebral hypoxia during sleep is associated with sleep-disordered breathing (SDB), aging and co-morbidities related to SDB. Eight proton magnetic resonance spectra for sleep and two for periods of arousal were obtained from the right centrum semiovale. All patients were evaluated for the presence or absence of co-morbidities including hypertension, cardiac disease, diabetes mellitus, and hyperlipidemia. Significant lactate signals were found in seven patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) during sleep periods, and none during periods of arousal. Aging was significantly related to the presence or absence of significant lactate signals during sleep periods as determined by logistic regression analysis (beta=0.2480; 95% confidence interval, 0.0905-0.5094; P=0.0001). Apnea index (AI), apnea-hypopnea index (AHI), and minimum value of peripheral oxyhemoglobin saturation each significantly interacted with age (P=0.0081, 0.0284, and 0.0302, respectively). Our findings suggest that SDB combined with aging is related to accumulation of lactate during sleep.

Sleep Apnea Syndrome Examination of Pharyngeal Obstruction with High-Speed MR and Polysomnography

Purpose: We attempted to determine the usefulness of high-speed MR imaging for evaluating the severity of sleep apnea syndrome (SAS) by comparing findings of pharyngeal obstruction obtained with high-speed MR with those of all-night polysomnography (PSG). Subjects and Methods: A total of 33 patients with SAS underwent turbo-FLASH MR examination, while awake and after i.v. injection of hydroxyzine hydrochloride. Serial images were examined by cinemode. Pharyngeal findings on MR were divided into single-site obstruction (SO) at the velopharynx, multiple-site obstruction (MO), and no obstruction (NO). PSG findings were analyzed to determine the predominant type of apnea, severity as evaluated by an apnea index (AI), and the lowest SaO2 value during sleep. Results: Seventy-five percent of the central apnea group had SO, and 70% of the mixed apneas had MO, while only 15% of the obstructed apneas had MO. The percentage of patients with severe SAS (AI of 20% or higher) was 48% for the SO, and 70% for the MO. The lowest SaO2 value tended to be low in the mixed apnea in the case of PSG, and tended to be low in the MO at MR examination. Conclusion: Analysis of pharyngeal dynamics using high-speed MR may provide some useful information for evaluating the severity of SAS.

Clinical significance of upper airway obstruction pattern during apneic episodes on ultrafast dynamic magnetic resonance imaging.

OBJECTIVES In order to assess the relationship between upper airway obstruction pattern and the clinical characteristics of obstructive sleep apnea syndrome (OSAS), we evaluated dynamic changes in the pharyngeal airway of patients with the disorder by using ultrafast dynamic magnetic resonance imaging (MRI). METHODS MRI while asleep was performed on 31 patients with OSAS (29 men, 2 women; mean age, 46.6+/-8.2 years; mean body mass index, 26.7+/-4.9kg/m(2); mean AHI, 40.6+/-21.7episodes/h). Relationships between obstruction pattern focusing on differences between single-site obstruction (SO) and multiple-site obstructions (MO) and titrated value of nasal CPAP in addition to respiratory variables were investigated. RESULTS The velopharynx (VP) was the main obstructive site among most of the cases with SO (17 of 18 cases), and all of the cases with MO (n=13) showed obstruction at and below the VP. AHI was significantly higher in cases with MO than in those with SO (P<0.01). As for SaO(2) variables, minimum value during sleep was significantly lower and total time with SaO(2) pound90% was longer in cases with MO than in those with SO (P<0.05 each). Titrated value of n-CPAP was also significantly higher in cases with MO than in cases with SO (P<0.05). CONCLUSIONS Our results strongly suggest that formation of MO manifested on ultrafast dynamic MRI could be related to increased severity of the disorder. Considering the higher titrable value of CPAP, MO could be brought about by high pharyngeal pressure.

Chondroitin Sulfate Iron Colloid as MR Contrast Agent in Differentiation between Hepatocellular Carcinoma and Adenomatous Hyperplasia

Using a 1.5 T MR imaging unit, T1- and T2-weighted images were obtained before and after i.v. administration of chondroitin sulfate iron colloid (CSIC) in order to differentiate hepatocellular carcinoma (n = 20) from adenomatous hyperplasia without atypia (n = 16). Differentiation was made from the tumor-liver contrast to noise ratio (CNR) and visual evaluation of the nodule, with reference to signal intensity relative to that of the surrounding liver. The CNR of adenomatous hyperplasia was on T1-weighted images significantly decreased after CSIC administration (p < 0.01). On T2-weighted images, there was no significant difference in CNR after CSIC administration. On the other hand, the CNR of hepatocellular carcinoma was significantly increased after CSIC administration on both T1- and T2-weighted images (p < 0.01). CSIC reflects intratumor reticuloendothelial cellular functions, and is therefore useful in differentiating hepatocellular carcinoma from adenomatous hyperplasia without atypia.

Chondroitin sulfate iron colloid as an MR contrast agent for the hepatic reticuloendothelial system.

Objective Chondroitin sulfate iron colloid (CSI), a therapeutic agent for asiderotic anemia, is widely used in the clinical field, and its safety has been established in Japan. We studied the potential of this agent for MRI of the hepatic reticuloendothelial system. Chondroitin sulfate iron colloid has a paramagnetic trivalent iron ion and is effective in shortening T2 relaxation time because it is taken up rapidly in the hepatic reticuloendothelial system after intravenous injection. Materials and Methods Hepatic MR images were obtained before and 1 h after the intravenous injection of 26.9 μmol Fe/kg of CSI in rats with experimentally induced tumors and of 18–30 μmol Fe/kg in human subjects. Results The signal intensities of normal hepatic tissue were decreased in all cases, whereas those of tumors were unchanged after CSI injection in these two series. Consequently, good contrast was observed in each pulse sequence. Conclusion Therefore, CSI seems to be clinically useful as a contrast agent for hepatic MRI.

Relationship between hypersomnia and respiratory disorder during sleep in Prader–Willi syndrome

Abstract To assess whether hypersomnia in Prader–Willi syndrome (PWS) patients is related to the respiratory disorder during sleep (RDDS), we made a systematic evaluation regarding the relationship between the two disorders in three patients. All patients showed hypersomnia manifested as the long duration of night sleep and shortened sleep latencies of multiple sleep latency test. Although magnetic resonance imaging and laboratory studies revealed obstruction of the upper airway and mild increase of esophageal pressure during sleep, the number of other apneic episodes or awakenings was not as frequent. From the above results, we speculate that the mechanism of excessive daytime sleepiness in PWS is not caused by RDDS and quite resembles that of essential hypersomnia.

Comparison of various techniques of iron oxide-enhanced breath-hold MR imaging of hepatocellular carcinoma

The purpose of our study is to compare qualitatively and quantitatively the abilities of various superparamagnetic iron oxide (SPIO)-enhanced breath-hold magnetic resonance imaging (MRI) techniques to detect hepatocellular carcinoma (HCC). Eight patients with HCCs were imaged. The images were obtained with conventional T2-weighted spin-echo imaging (CSE), half-Fourier single-shot turbo spin-echo (HASTE), single-shot gradient-echo type echo planar imaging (GE-EPI), and single-shot spin-echo type echo planar imaging (SE-EPI) before and after SPIO administration. The liver signal-to-noise ratios (SNRs) in CSE and each EPI sequence were significantly decreased after SPIO administration. GE-EPI had the highest decrease ratio (DR) of liver SNR, followed by SE-EPI (TE=98), SE-EPI (TE=28), CSE, and HASTE in this order. The relative contrasts with GE-EPI and SE-EPI (TE=98) were significantly higher than that with CSE after SPIO administration. On receiver operating characteristic (ROC) analysis, diagnostic accuracy did not differ significantly among the pulse sequences after SPIO administration. GE-EPI and SE-EPI (longer TE) were useful for SPIO-enhanced breath-hold MRI performed to detect HCC.

Asymptomatic membranous obstruction of the inferior vena cava forming intrahepatic collateral pathways

Intrahepatic and/or extrahepatic collateral pathways result from the membranous obstruction of the inferior vena cava. These collaterals are usually insufficient to prevent Budd-Chiari syndrome. We reprot an unusual case of asymptomatic membranous obstruction of the inferior vena cava in which marked intrahepatic collateral pathways were formed. Although the inferior vena cava terminated above the orifice of the right hepatic vein, the middle and left hepatic veins were patent above the membrane, without narrowing. Blood from the inferior vena cava drained into the right atrium via the intrahepatic collaterals between the right and middle hepatic veins without resistance.